1997 993 Intermittent Engine Surge at Slight Throttle

Vehicle Information: Model: 993 ; Year: 1997; Body Type: Cabriolet; Total Mileage: 78,363;

I want to thank you again for this great resource and your expertise. I searched and did not see any responses to my specific question, so I apologize in advance if I missed the answer. Every once in a while I have noticed that my car has an engine surge once it is fully warmed up and under low throttle (b/t 2,000 to 3,000 RPM in any gear). It as if the cruise control had kicked in for a second to accelerate the car for just a half a second. It happened most recently on the highway yesterday when I was cruising at 2,600 RPMs. There was a sudden slight surge even though I was holding the throttle steady. What electrical gremlin could be causing this? I have owned the car for a year and a half and this has happened about 4 or 5 times. It is not a huge deal, but is disconcerting when it has occured in tight traffic situations.Thank you for your help!